Refrigeration system for delivery trucks



Oct. 25, 1960 H. B. PARKER REFRIGERATION SYSTEM FOR DELIVERY TRUCKS 2Sheets-Sheet 1 Filed Dec. 20, 1956 Harold B. Parke r IN V EN TOR.

H. B. PARKER REFRIGERATION SYSTEM FOR DELIVERY TRUCKS Oct. 25, 1960 2Sheets-Sheet 2 Filed Dec. 20, 1956 .nillilllllllll ll'l'll l'l ll IHarald B. Parker INVENTOR. By fimm WW REFRIGERATION SYSTEM FOR DELIVERYTRUCKS Harold B. Parker, Loudenville, Ohio, assignor to ParkerRefrigeration Development Co., a corporation of Ohio Filed Dec. 20,1956, Set. N0. 629,603

4 Claims. (31. '62186) The present invention relates to refrigerationsystems and more particularly relates to an apparatus specificallyadapted for installation in a delivery truck employed in thedistribution of products that are necessarily maintained within apredetermined low temperature range at all times.

In present day construction of delivery trucks and especially deliverytrucks for dairy products such as milk, it is necessary that the milk beretained at a predetermined low temperature generally ranging from 34 to40 F. Certain standards have been set up by various health departmentsand'such standards include the requirements that any milk beingsubjected to a temperature more than 40 must be brought back to the milkprocessing plant for use in the production of other products since thevarious regulatory bodies such as health departments will not permit thedistribution of milk if it is subjected to the higher temperaturesduring delivery by the delivery truck. In solving the problem, thegeneral procedure is the provision of a relatively thick and extremelyheavy unit in the top of the insulated load carrying body with the unitbeing filled; with a holding fluid with various eutectic fluids beingemployed for this purpose. Normally, the fluids are lowered, to atempera ture much below the desired temperature and in fact approachzero degrees F. Due to the large quantity of this fluid, the temperaturein the insulated load carrying space will be maintained at the desiredlevel-if the doors into the insulated space are not opened: toofrequently and if the load is emptied relatively rapidly. When it occursthat trafiic conditions delay delivery of the products or increasedcooling load is produced due to exceedingly high outside temperature ordue to opening of the compartment or placing warm empty bottlesand-cases therein, the cold holding fiuid will not adequately maintainthe temperature in the load carrying compartment below the allowablemaximum level.

Another shortcoming of the cold hold unit. presently employed is thetendency of the extremely low temperatures encountered adjacent the coldhold unit sometimes freeze the uppermost products. This also renders themilk unusable and causes damage to the bottles containing the same dueto the expansion of the milk during freezing. Also, the exceedinglyheavy weight of the cold hold unit which approaches 500 pounds requiresan extra heavy reinforced construction for the truck body and even withsuch reinforcement, this high weight in the top of the body causesdamage thereto due to movement caused by rought pavement thus reducingthe useful life of the insulated body and reducing the insulationqualities thereof.

In view of the various objectionable features of the cold hold unit, Ihave provided a refrigeration system adapted especially for milkdelivery trucks which is exceedingly light in construction, efficient inoperation, easily installed without additional reinforcing, accuratelycontrolled for maintaining a desired temperature in the 2,957,317Patented Oct. 25, 1960 ice load carrying compartment and yet relativelyinexpensive to install and maintain.

In carrying out the above objects, I provide a pair of cold holdingunits of light weight construction mounted in the top of an insulatedbody and separated generally from the load carrying space by a bafileplate having an opening therein with the opening being provided with anair circulating fan that is thermostatically controlled for circulatingair over and under the cold holding units thus providing effectivecontrol for the temperature of the air with the cold holding units beingprovided with condensed refrigerant by the use of a compressor drivenfrom the internal combustion engine of the delivery truck during normaloperation of the truck with the compressor being driven by an auxiliarymotor when the delivery truck is inoperative such as when stored in agarage thus permitting the delivery truck to be employed as a storagearea for the milk immediately atfer it is processed and disposed inbottles whereby the alternative driving of the compressor isaccomplished by employing a double pulley arrangement with an overridingclutch preferably of the magnetic type. A small fan is provided on theauxiliary electric motor for circulating air over the condensor therebyenabling the refrigeration cycle to operate in periods of normaloperation of the delivery truck when the internal combustion engine isbeing operated for driving the truck and when the truck is garaged orotherwise storedovernight thus maintaining the milk at a desiredtemperature as determined by thermostatic controls for the evaporatorvalve as well as the circulating fan in the refrigeration system.

These together withother objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numeralsrefer to like parts throughout, and in which:

Figure l is. a schematic View of the refrigeration system. of, thepresent invention installed on a conventional delivery truck having aninsulated load carrying body;

Figure 2- is a fragmentary perspective view of the construction. of thecold holding unit, the bafiie plate and the arrangement of the fantherein. as viewed from the rear of the body;

Figure 3 is. a longitudinal, vertical sectional view taken substantiallyupon. a. plane passing along section line 3-3 of; Figure 2 illustratingspecific structural details of the various features of the invention;

Figure 4 is a transverse sectional view taken substantially upon a planepassing along section line 4-4 of Figure 2 illustrating furtherstructural arrangements of the present invention; and I Figure 5 is afragmentary sectional view taken generally upon a plane passing alongsection line 5-5 of Figure 3 illustrating a drain opening for the bafileplate for permitting discharge of any condensate which may collect onthe baffle plate.

Referring now specifically to the drawings, the delivery truck isgenerally designated by the numeral 16 and includes an insulated loadcarrying body 12 and a cab and hood assembly 14 which is of conventionalconstruction which is equipped with the usual ground engaging wheels 16,internal combustion engine 18 and other features normally em-ployed in aconventional delivery truck including a radiator for the engine 18 and agrill opening 20 for permitting cooling air to be circulated in relationthereto. The truck body 12 will generally include an outer wall 22 andan inner wall 24 held in spaced.rela tion'to each other by structuralmembers 26 with the area therebetween being filled with insulationmaterial if desired. The rear end of the truck body 1Z'is provided withopenable hinged doors 28 and a front wall 30 which may have a movablepartition or section 31 permitting access into the interior of the body12 from the drivers compartment of the truck 10. The aforementionedconstruction is conventional and forms no part of the present inventionexcept in its orientation to the refrigeration system of the presentinvention.

The refrigeration system incorporates a pair of cold holding fluid unitsgenerally designated by the numeral 32 which is the equivalent of anevaporator in the usual refrigeration system together with an expansionvalve generally designated by the numeral 34, a compressor 36, acondensor 38, a receiver tank 40 and a dehydrator 42. The compressor 36is mounted in the engine compartment and is driven from a power take-offthrough a V-belt 44 from the engine 18 to a pulley 46 for driving aninput shaft 48 of the compressor 36 thereby driving the compressor inthe usual manner. The compressor 36 may be of conventional constructionand one which is commercially available for vehicle mounting such asemployed in passenger automobile air conditioning units. The pulley 46is provided with an overriding clutch of the magnetic type with anycommercially available type of overriding clutch being acceptable forpermitting the compressor 36 to be driven by the V-belt pulley 44 in onedirection of rotation when power is being supplied from the internalcombustion engine 18 but will permit the pulley 46 to idle freely whenthe shaft 48 is being driven by an auxiliary pulley 50 mounted on theinput shaft 48 of the compressor 36 The auxiliary pulley 50 is drivenfrom an electric motor 52 through a V-belt drive 54 wherein the electricmotor 52 is provided with an electrical plug-in adapter (not shown) forassociation with an electrical outlet for driving the compressor 36 whenthe truck is parked or garaged. The electric motor 52 also drives asmall air circulation fan 56 for circulating air over the condensor 38when the motor 52 is being used to drive the compressor 36 for causingsuflicient air movement to cool the condensor 38. The condensor 38 mayalso be of any conventional construction such as the finned tube typeand is normally mounted forwardly of the radiator and behind the grillopening so that air will pass over the condensor 38 when the deliverytruck'is in normal forward motion as when the compressor '36 is beingdriven from the internal combustion engine during the delivery of theproducts.

The compressor 36 has a suction line 58 connected thereto for receivinghot gaseous refrigerant from the evaporator unit 32 and a high pressuredischarge line 60 interconnects the compressor 36 and the condenser 38for cooling the high pressure hot refrigerant gas after which thecondensed refrigerant gas is received in the receiver tank 40 and thereceiver tank 40 is connected to the expansion valve by conduit 62 withthe dehydrator 42 being arranged in the conduit 62. The expansion valve34 is disposed in the conduit 62 and is connected to the evaporator unit32 with the evaporator unit 32 including cold holding units 64 and 66connected in series by a connecting line 68 with the return line 58being connected to the rear end of unit 66 remote from the connection ofline 62 with the unit 64.

Each cold holding fluid unit 64 and 66 includes spaced plates 68 and 70joined together at the peripheral edges as designated by numeral 72 witha refrigerant coil 74 disposed therein with the area between the plates68 and 70 being completely filled with a eutectic holding fluid whichmay be of any type which will permit such fluid to be reduced to atemperature such as zero degrees F. wherein the entire unit will becompletely solidified. The refrigerant coil 74' may be of anynon-corrosive substance and the plates 68 and 70 may be of plastic orthe like and this construction together with the fluid 76 is relativelylightweight in construction. For supporting the units 64 and 66, aplurality of inverted channel shaped support members 78 are provided intransverse relation to the body 12 with the ends of the channel shapedmembers 78 being mounted on suitable brackets 80.

Disposed in underlying relation to the evaporator unit 32 is a baflieplate 82 havingan upturned peripheral edge 84 that is supported by aplurality of depending brackets 86 secured to the inner wall 24 andincluding inturned lower ends 88 forming a plurality of ledges fordetachably supporting the baflle plate 82. The baffle plate 82 isprovided with an enlarged centrally disposed opening 98 having a Wiregrill or grid 92 supported therein as by projecting lugs 94 on the wiregrid engaging the edges of the opening 90. The opening is generally inalignment with afan 96 powered by an electric motor 98 with the fan unitbeing supported from a bracket 100 which is also suspended from theinner wall 24. The fan 96 is generally arranged in alignment'with theunits 64 and 66 and above the baffle plate 82. Downwardly extendingbaffle plates 102 are provided forwardly and rearwardly of the fan 96thereby assuring that air drawn through the opening 90 will pass aboveand below the units 64 and 66 and along the upper and lower surfacethereof for effectively cooling the air. The fan 96 may be disposed inany vertical orientation in relation to the cold holding units 64 and 66to assure that air will pass both below and above these units.

The baffle plate 82 is provided with a depending drain line 184 adjacentone corner thereof for draining any condensate which may be deposited inthe baflie plate 82. The baffle plate 82 may be provided with a falltowards this corner or normal shifting of the truck during operationthereof may be relied upon for draining any condensate and in thisinstance, an upstanding flange may be provided on the opening 90 toprevent any condensate from'dripping onto the contents of the truckbody.

The expansion valve 34 may be of any conventional construction and iscontrolled by heat bulbs 106 and 108 with one heat bulb 106 beingdisposed at the inlet side of the first unit 64 and the other heat bulb108 being connected to the transfer line 68 interconnecting the units 64and 66. Each of the heat bulbs 106 and 108 is provided with the usualtube 110 extending back to'the expansion valve 34 for controllingoperation thereof in response to the temperatures of the refrigerantprogressing throughthe evaporator unit 32.

The fan 96 is thermostatically controlled from thermostatic heat bulb112 located on the inner wall of the body and is connected to a controlswitch 114 through the usual capillary tube 116 for controllingoperation of the fan 96 in direct relation to the temperature in theinterior of the load carrying compartment whereby the air in the loadcarrying compartment will be immediately circulated in the event thetemperature approaches the maximum for which the system is adjusted. Itis noted that the evaporator unit 32 is in spaced relation to the sideWalls of the body whereby the air will be drawn upwardly from the centerof the load carrying compartment and the cold air will be discharged atthe edges thereof thus providing adequate air circulation formaintaining a substantially constant temperature throughout the volumeof the body. Any type of fan may be provided and a manual control mayalso be provided if desired. The baifle plate 82 also prevents anypossible freezing of the pay load since the holding fluid 76 may becarried down to very low temperature without danger of freezing theuppermost portions of the pay load. 'Any type of refrigerant may beemployed in the system although Freon 12 .has been successfully employedand another feature not shown is the provision of a trickle charge forthe battery of the delivery truck whereby the battery may also be fullycharged during periods of-operation of the refrigeration system by theauxiliary motor 52 as when the auxiliary motor is plugged into anelectrical outlet. 'The fan in combination with the largesurface area ofthe evaporation unit 32 will effectively provide flash cooling of hot N.NE

air permitted to enter the load carrying compartment as when the doorsare opened for removal of or placement of articles therein therebyeffectively maintaining a constant temperature regardless of the suddenchanges in the heat load with the sudden increase in the heat load onlytending to melt or raise the temperature of the holding fluid 76 and notthrowing any heavy load on the refrigeration system which may betemporarily inactive due to temporary parking of the delivery truck.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly, all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention asclaimed.

What is claimed as new is as follows:

1. A refrigeration system for a delivery truck having an insulated payload compartment comprising a compressor, a condenser, a receiver, anexpansion device and an evaporator located in communication for forminga refrigeration cycle, said evaporator being mounted in the roof of theinsulated compartment and including a pair of cold holding unitssuspended in spaced relation to the roof of the compartment, a baflieplate disposed under said units, each of said units including spacedplastic walls capable of expansion and contraction without damage with arefrigerant passage therebetween and a freezable cold holding fluidcompletely filling each unit, and means forcing circulating air over theexternal surfaces of the walls of said units for controlling thetemperature of the pay load compartment, said means for circulating airincluding a fan disposed between said units for circulating air againstthe upper and lower surfaces of each unit for effectively cooling theair due to skin contact of the air with the exterior surfaces of thewalls of the units, said bafile plate having a central apertureunderlying the fan and directing the fiow of air over the units, saidbafile plate being disposed in spaced relation to each unit, the centralopening forming an intake for the air circulating fan, and bafile meansdisposed at the ends of the cold holding unit and spaced from the sidewalls of the pay load compartment for assuring circulation of air overthe side edges of the unit and transverse movement of such air, saidbaflie plate including upturned edges and a downwardly extending drainconduit extending through the wall of the compartment for drainingcondensate to the exterior of the compartment thereby preventingdrippage of condensate onto the pay load while isolating the pay loadfrom the cold holding units for preventing freezing of the pay load.

2. In combination with a delivery truck for refrigerated products havingan insulated pay load compartment, a refrigeration system comprising acompressor driven from the engine of the truck, a condenser cooled bymovement of the truck, and an evaporator unit mounted in the top of thepay load compartment, said evaporator unit ineluding a cold holdingfluid unit, a baflie plate disposed in spaced relation below said fluidunit for separating the fluid unit from articles in the compartment,said plate having a centrally disposed opening therein forming an airinlet, a fan disposed above the plate for drawing air through theopening and forcing the air over the fluid unit for cooling the air,said fan being thermostatically controlled in response to thetemperature in the compartment.

3. The combination of claim 2 wherein said cold holding fluid unitincludes a pair of enlarged spaced parallel rigid plates of plasticmaterial having the peripheral edges thereof sealed together, anevaporator tube disposed between said plates, eutectic fluid completelyfilling the remainder of the area between the plates whereby evaporationof a liquid refrigerant in the evaporator tube will solidify theeutectic fluid and lower the entire outer surface of the plates to thetemperature of the solidified fluid, the plastic material of the platescompensating for the expansion and contraction of the eutectic fluidduring the changes in state thereof.

4. The combination of claim 3 wherein said bafile plates includeupturned edges and a downwardly extending drain conduit extendingthrough the wall of the compartment for draining condensate to theexterior of the compartment thereby preventing drippage of condensateonto the pay load while isolating the pay load from the cold holdingunit for preventing freezing of the pay load.

References Cited in the file of this patent UNITED STATES PATENTS1,966,164 Clark July 10, 1934 2,013,848 Heideman Sept. 10, 19352,178,807 Ploeger Nov. 7, 1939 2,463,835 Warren Mar. 8, 1949 2,602,302Ponx July 8, 1952 2,635,432 Kleist Apr. 21, 1953 2,694,297 ShoemakerNov. 16, 1954 2,774,222 Jacobs et al. Dec. 18, 1956 2,902,840 SmithSept. 8, 1959

